How Much Context Is Enough? Two Cases of Span-Conditioned Stem Allomorphy

Greek voice and aspect jointly condition verbal stem allomorphy, including suppletion. Negation and tense in English do likewise. These cases show that stem allomorphy cannot be restricted to cases where the conditioning element is structurally adjacent to the element that displays allomorphic variation. But neither is contextual allomorphy entirely free from locality constraints: allomorphy can be conditioned only by a span, a contiguous set of heads in an extended projection.